1. Field of the Invention
The present invention relates to improvements in or to a control apparatus for hydraulically operated automatic multiple-speed transmissions for use in vehicles.
2. Description of the Prior Art
In the conventional hydraulically-controlled automatic transmissions which provide three forward gear ratios, for example, an intermediate gear, or second speed, is provided by engaging the following elements: one one-way clutch F.sub.1, a brake B.sub.2 acting on the clutch F.sub.1, a brake B.sub.1 for acting on the engine brake or compensating for insufficient capacity of the aforementioned clutch F.sub.1, and a forward clutch C.sub.1. Shifting gear ratios from the first to second speed takes place by engaging the brake B.sub.2 to enable the transmissions to be synchronized with the second speed, and completed by later engaging the brake B.sub.1. Shifting down from the third to second speed is completed by first engaging the one-way clutch F.sub.1 securely held by the brake B.sub.2 and by then engaging the brake B.sub.1. To control the timing at which the brake B.sub.1 is to be engaged for upshifting first to second and for downshifting third to second. Individual sequence valves are provided within the hydraulic control circuit. If the reverse clutch C.sub.2 which engages for changing to reverse gears is equipped with a dual piston assembly including an inner piston and an outer piston, an additional individual sequence valve is required to control the timing for the operating sequence of the two pistons.